Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$164.46	10.706%	$182.0671	$182.07	$182.05	$182.10
Purchase #2	$115.38	7.275%	$123.7739	$123.77	$123.75	$123.80
Purchase #3	$170.77	11.693%	$190.7381	$190.74	$190.75	$190.70
Purchase #4	$161.47	12.536%	$181.7119	$181.71	$181.70	$181.70
Purchase #5	$171.64	5.718%	$181.4544	$181.45	$181.45	$181.50
Purchase #6	$199.69	4.846%	$209.367	$209.37	$209.35	$209.40
Purchase #7	$60.49	3.674%	$62.7124	$62.71	$62.70	$62.70
7 purchase totals =	$1,043.90		$1,131.8248	$1,131.82	$1,131.75	$1,131.90